package cn.edu.sdjzu.xg.bysj.domain;

public class Pagination {
    public Pagination(int pageSize, int pageNo) {
        // 防止错误赋值
        if (pageNo > 0) {
            this.pageNo = pageNo;
        }else {
            this.pageNo = 5;
        }

        if(pageSize > 0){
            this.pageSize = pageSize;
        }else {
            this.pageSize = 1;
        }
    }

    // 返回LIMIT子句
    public String toLimitClause(int totalNum){
        // 向前台提供元组总数
        this.totalNum = totalNum;
        // 偏移量
        int offset = (this.pageNo - 1) * this.pageSize;
        // 输出LIMIT子句，注意关键字两端的空格
        return " LIMIT " + offset + "," + this.pageSize;
    }

    // 如果没有get方法，fastjson将无法读取对象属性
    public int getPageSize(){
        return this.pageSize;
    }

    public int getPageNo(){
        return this.pageNo;
    }

    public int getTotalNum(){
        return this.totalNum;
    }

    // 每页的对象（元组）数
    private int pageSize = 5;
    // 页号
    private int pageNo = 1;
    // 对象（元组）总数
    private int totalNum = 1;
}
